As I see it you need these tables:
CREATE TABLE Categories (
catid INT AUTO_INCREMENT PRIMARY KEY,
CREATE TABLE Countries (
coid INT AUTO_INCREMENT PRIMARY KEY,
CREATE TABLE Customers (
custid INT AUTO_INCREMENT PRIMARY KEY,
coid INT FOREIGN KEY REFERENCES countries(coid),
CREATE TABLE Offers (
offerid INT AUTO_INCREMENT PRIMARY KEY
catid INT FOREIGN KEY REFERENCES categories(catid),
offerdetails .... one or more fields to describe the offer ...
CREATE TABLE OffersByCountry (
offerid INT FOREIGN KEY REFERENCES offers(offerid),
coid INT FOREIGN KEY REFERENCES countries(coid)
CREATE TABLE CompletedOffers (
custid INT FOREIGN KEY REFERENCES custormers(custid),
offerid INT FOREIGN KEY REFERENCES offers(offerid)
The foreign key reference in magenta
there may not be necessary, but it is likely a good idea.
The syntax there for the foreign keys isn't quite correct for MySQL, but it's a compact form that easy to read for a post like this.