@Denni1016 Most hosts who do longer-term stays do a mid-stay clean, or a bi-weekly, or whatever seems reasonable. The reason isn't as much cleanliness, as it is keeping an eye on your property. You want to be able to get a sense of if the guest is keeping the place clean, or trashing your property.
The best way to handle it is to have it in your house rules, i.e. any stays over x days will have periodic cleaning. It has to be arranged with the guest, of course- you can't just march in and start cleaning- but if it's in your house rules, they have to comply. Make sure to include a reminder with any long-term bookings before they arrive.
Basically, a change of linens and towels, and perhaps a quick vacuum and wipe-down of the bathroom. It doesn't have to be a turnover clean, but it will likely make the guest happy and more comfortable during their stay, and it will give you the opportunity to keep an eye on things. If you get any pushback, don't budge. Get that firmly established before they arrive.
Good luck.