So, I guess give her a bigger envelope.  8o)

I think a dinner out would be a nice way to show appreciation, or maybe a little bauble or a gift card to her favorite store.

I had a 20th (you read that right) with a gal last year.

We did an overnight at a five star and a sumptuous feast.

I'm wondering what I'll do for our 40th.

So I keep track of my hobby expenses by logging dates and amounts spent.   Did I really spend that much that month? lol.

I noticed that my current ATF and I have a first anniversary coming up shortly.   This will be the first time I've ever stuck with a provider for this long.  7 months was the longest I think.

Besides the obvious, any suggestions?

Does it seem like a bit much to be marking such an anniversary?  

I'm wondering if I should buy her something or not.

Doesn't seem like too much to me. I recommend sending her a Victoria Secrets gift card via E-mail, suggest she use it to buy something sexy to surprise you with, and then arrange for an overnight, complete with wine, a jacuzzi, etc. Should be awesome!

What do you expect from her?  Do you think she will even know that it's your "anniversary"?

That said, if you want to do something small to make it special, I don't see a problem but I wouldn't go overboard.

Why, yes, it does!  First of all, you'd better be damn sure she even remembers.  Most providers wouldn't, I'll bet.  She's not your girlfriend.  Please don't confuse her as such, you may find it embarassing.

Take her out or make a dinner or get take out, if your doing multi hours.  If it is a short visit a good bottle of wine or champange and caviar or friut.  Do not forget a gift or gift card of of her gift list.

I just had an AMP provider remember me from a bit over a year ago.  Now, I actually hope she does not have the date recorded anywhere, and she didn't claim it was our anniversary.  But then I've only seen her twice, then and a week ago, and she works in a different joint, and I didn't remember her at all.
Some of these ladies are on designer drugs and may not remember you tomorrow, but others will remember with great accuracy, even after a gap of multiple years.  Some will be using top of the line database systems that we can only hope have major security built in.  
Frankly, unless you are a celeb, she isn't likely to list you in her memoirs....I don't ever plan on running for office.
And to answer the original question, if the dude has been seeing the lady on a regular basis, hell year!  Take her out somewhere nice if you can be seen in public, or order in and provide good wine and chocolates, as well.

And I always have.

Later this month I'm celibrating my first anniversary with a new Mistress arrangement and we're going to Europe (granted that's WAY more then could be expected so I acknowledge I'm being spoiled).

This May I celebrate my 6th anniversary with my another gent. We'll be going up to a cabin to do some hiking, star gazing, scotch sipping and screaming loud sex without having to worry about disturbing the neighbors lol

My suggestions: Take her out to a lovely dinner, share some champagne and laughter.  Maybe buy her a manicure/pedicure package at a salon.  I'm sure in the year that you've known her there is much you've talked about. A collectors version of a book she loves.  Something based on an inside joke, or a hobby, or maybe she's talked about some little thing she's wanted.  If she's got any financial concerns or debt, and your in a position to give something small towards that I'm sure that would be appreciated.

Whatever you do, do think about giving her a fun or pretty card, and write her a note inside, mentioning that she's is indeed the only woman you've stuck with for that long, and let her know what it is about her that draws you back.  It's nice to be appreciated and feel like more then a purchasable commodity.

Congratulations on finding someone that can bring you joy

I do not think I would ever help with finances for an anniversary with a companion.   It seems so impersonal, like, "oh yea, we've been doing this for a year(s) and I should give her something because I want XXX"  Not how I roll...I don't do gift cards for friends and family either, same reason only the something XXX is more like ABC...

If you've been doing this a while, you should know something she actually wants.  I just met a new companion this week and I know three things she would want, and she didn't even specifically tell me she wanted them!